Method for fabricating an ultralow dielectric constant material as an intralevel or interlevel dielectric in a semiconductor device and electronic device made

ABSTRACT

A method for fabricating a thermally stable ultralow dielectric constant film comprising Si, C, O and H atoms in a parallel plate chemical vapor deposition process utilizing a plasma enhanced chemical vapor deposition (“PECVD”) process is disclosed. Electronic devices containing insulating layers of thermally stable ultralow dielectric constant materials that are prepared by the method are further disclosed. To enable the fabrication of a thermally stable ultralow dielectric constant film, specific precursor materials are used, such as, silane derivatives, for instance, diethoxymethylsilane (DEMS) and organic molecules, for instance, bicycloheptadiene and cyclopentene oxide.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to co-assigned U.S. Pat. Nos.6,147,009, 6,312,793, 6,441,491, 6,437,443, 6,541,398, 6,479,110 B2, and6,497,963, the contents of which are incorporated herein by reference intheir entirety. The present application is also related to co-pendingand co-assigned U.S. patent application Ser. Nos. 10/174,749, filed Jun.19, 2002, Ser. No. 10/340,000, filed Jan. 23, 2003, Ser. No. 10/390,801,filed Mar. 18, 2003, and Ser. No. 10/758,724, filed Jan. 16, 2004, thecontents of each of the aforementioned U.S. patent applications are alsoincorporated herein by reference in their entirety as well.

FIELD OF THE INVENTION

The present invention generally relates to a method for fabricating adielectric material that has an ultralow dielectric constant (orultralow k) and an electronic device containing such a dielectricmaterial. More particularly, the present invention relates to a methodfor fabricating a thermally stable ultralow k film for use as anintralevel or interlevel dielectric in an ultra-large-scale integration(“ULSI”) back-end-of-the-line (“BEOL”) wiring structure and anelectronic structure formed by such a method.

BACKGROUND OF THE INVENTION

The continuous shrinking in dimensions of electronic devices utilized inULSI circuits in recent years has resulted in increasing the resistanceof the BEOL metallization as well as increasing the capacitance of theintralayer and interlayer dielectric. This combined effect increasessignal delays in ULSI electronic devices. In order to improve theswitching performance of future ULSI circuits, low dielectric constant(k) insulators and particularly those with k significantly lower thansilicon oxide are needed to reduce the capacitances. Dielectricmaterials (i.e., dielectrics) that have low k values are commerciallyavailable. One such commercially available material, for example, ispolytetrafluoroethylene (“PTFE”), which has a dielectric constant ofabout 2.0. Most commercially available dielectric materials however arenot thermally stable when exposed to temperatures above 300° C.Integration of low k dielectrics in present ULSI chips requires athermal stability of at least 400° C.

The low k materials that have been considered for applications in ULSIdevices include polymers containing elements of Si, C, O and H, such asmethylsiloxane, methylsilsesquioxanes, and other organic and inorganicpolymers. For instance, a paper (N. Hacker et al. “Properties of new lowdielectric constant spin-on silicon oxide based dielectrics” Mat. Res.Soc. Symp. Proc. 476 (1997): 25) describes materials that appear tosatisfy the thermal stability requirement, even though some of thesematerials propagate cracks easily when reaching thicknesses needed forintegration in an interconnect structure when films are prepared by aspin-on technique. Furthermore, these prior art precursor materials arehigh cost and prohibitive for use in mass production. Moreover, most ofthe fabrication steps of very-large-scale-integration (“VLSI”) and ULSIchips are carried out by plasma enhanced chemical or physical vapordeposition techniques.

The ability to fabricate a low k material by a plasma enhanced chemicalvapor deposition (PECVD) technique using previously installed andavailable processing equipment will thus simplify its integration in themanufacturing process, reduce manufacturing cost, and create lesshazardous waste. U.S. Pat. Nos. 6,147,009 and 6,497,963 describe a lowdielectric constant material consisting of elements of Si, C, O and Hatoms having a dielectric constant not more than 3.6 and which exhibitsvery low crack propagation velocities.

U.S. Pat. Nos. 6,312,793, 6,441,491, 6,541,398 and 6,479,110 B2 describea multiphase low k dielectric material that consists of a matrix phasecomposed of elements of Si, C, O and H and another phase composed mainlyof C and H. The dielectric materials disclosed in the foregoing patentshave a dielectric constant of not more than 3.2.

U.S. Pat. No. 6,437,443 describes a low k dielectric material that hastwo or more phases wherein the first phase is formed of a SiCOHmaterial. The low k dielectric material is provided by reacting a firstprecursor gas containing atoms of Si, C, O, and H and at least a secondprecursor gas containing mainly atoms of C, H, and optionally F, N and Oin a plasma enhanced chemical vapor deposition chamber.

Despite the numerous disclosures of low k dielectric materials, there isa continued need for developing a dielectric material that has adielectric constant of not more than about 2.5, which has a low stressand thermal stability within processing temperatures used in currentULSI technologies.

SUMMARY OF THE INVENTION

The present invention provides a method for fabricating an ultralowdielectric constant (i.e., ultralow k) material having a dielectricconstant of not more than about 2.5. More preferably, the dielectricconstant for the ultralow k material that is provided in the presentinvention is from about 1.5 to about 2.5, and most preferably, thedielectric constant is from about 1.8 to about 2.25. It should be notedthat all dielectric constants are relative to a vacuum unless otherwisespecified.

The present invention also provides a method for fabricating an ultralowdielectric constant material comprising Si, C, O and H atoms from amixture of at least two precursors, wherein a first precursor isselected from silane (SiH₄) derivatives having the molecular formulaSiRR′R″R′″ where R,R′,R″, and R′″ may or may not be the same ordifferent and are selected from H, alkyl, and alkoxy. Preferably R, R′,R″ and R′″ are the same or different and are methyl, ethyl, methoxy, andethoxy. Preferred first precursors include, but are not limited to:diethoxydimethylsilane, diethoxymethylsilane(DEMS),ethoxyltrimethylsilane, ethoxydimethylsilane, dimethoxydimethylsilane,dimethoxymethylsilane, triethoxysilane, and trimethoxymethylsilane.

The second precursor employed in the present application is an organiccompound selected from:

-   -   where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and        are selected from hydrogen, alkyl, alkenyl or alkynyl groups        that may be linear, branched, cyclic, polycyclic and may be        functionalized with oxygen, nitrogen or fluorine containing        substituents. Preferred second precursors include, but are not        limited to: ethylene oxide, propylene oxide, cyclopentene oxide,        isobutylene oxide, 2,2,3-trimethyloxirane, butadienemonoxide,        bicycloheptadiene, 1,2-epoxy-5-hexene, 2-methyl-2-vinyloxirane,        1-isopropyl-cyclohexa-1,3-diene and tertbutylmethylether.

The use of the first precursor that includes a silane derivative incombination with the second organic precursor enables an efficientincorporation of a pore forming phase in a SiCOH matrix and thepreparation of SiCOH films at lower cost than with precursors describedin the prior art.

The use of the first precursor that includes a silane derivative incombination with the second organic precursor can enable a porous SiCOHdielectric having a reduced tensile stress, according to the methods ofthis invention.

The present invention further provides a method for fabricating anultralow k dielectric in a parallel plate plasma enhanced chemical vapordeposition (“PECVD”) reactor as well as a method for fabricating anultralow k material for use in electronic structures as an intralevel orinterlevel dielectric in a back-end-of-the-line (“BEOL”) interconnectstructure.

The present invention, in another aspect, also provides a thermallystable ultralow k material that has low internal stresses and adielectric constant of not higher than about 2.5. More preferably, thedielectric constant for the ultralow k material is from about 1.5 toabout 2.5 and, most preferably, the dielectric constant is from about1.8 to about 2.25.

In yet another aspect, the present invention provides an electronicstructure incorporating layers of insulating materials as intralevel orinterlevel dielectrics in a back-end-of-the-line (“BEOL”) wiringstructure in which at least two of the layers of insulating materialscomprise an ultralow k material of the present invention.

Still further, the present invention provides an electronic structure,which has layers of the inventive ultralow k material as intralevel orinterlevel dielectrics in a back-end-of-the-line (“BEOL”) wiringstructure and which further contains at least one dielectric cap layeras a reactive ion etch (“RIE”) stop or a chemical-mechanical polish stopor a diffusion barrier.

In accordance with the present invention, a method for fabricating athermally stable dielectric material that has a matrix comprising Si, C,O, and H atoms and an atomic level nanoporosity is provided. In apreferred embodiment, the dielectric material has a matrix that consistsessentially of Si, C, O, and H. The present invention further provides amethod for fabricating the dielectric material by reacting a firstsilicon-containing precursor gas comprising atoms of Si, C, O, and H andat least a second organic-containing precursor gas comprising atoms ofC, H, and optionally O, F and N in a plasma enhanced chemical vapordeposition (“PECVD”) reactor. The dielectric material of the presentinvention has an FTIR spectra having a Si—O absorption band that can bedeconvoluted into three peaks. The present invention further provides anelectronic structure (i.e., substrate) that has layers of insulatingmaterials as intralevel or interlevel dielectrics used in aback-end-of-the-line (“BEOL”) wiring structure, wherein the insulatingmaterial can be the ultralow k film of present invention.

In a preferred embodiment, there is provided a method for fabricating athermally stable ultralow k film comprising the steps of: providing aplasma enhanced chemical vapor deposition (“PECVD”) reactor; positioningan electronic structure (i.e., substrate) in the reactor; flowing afirst silicon-containing precursor gas comprising atoms of Si, C, O, andH into the reactor; flowing a second organic-containing precursor gasmixture comprising atoms of C, H and optionally O, F and N into thereactor; and depositing an ultralow k film on the substrate.

Preferably, the first precursor is selected from silane (SiH₄)derivatives having the molecular formula SiRR′R″R′″ where R,R′,R″, andR′″ may or may not be identical and are selected from H, alkyl, andalkoxy, preferably methyl, ethyl, methoxy, and ethoxy. Preferredprecursors include: diethoxydimethylsilane, diethoxymethylsilane (DEMS),ethoxyltrimethylsilane, ethoxydimethylsilane, dimethoxydimethylsilane,dimethoxymethylsilane, triethoxysilane and trimethoxymethylsilane.

The second precursor employed in the present application is an organiccompound selected from:

-   -   where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and        are selected from hydrogen, alkyl, alkenyl or alkynyl groups        that may be linear, branched, cyclic, polycyclic and may be        functionalized with oxygen, nitrogen or fluorine containing        substituents. Preferred second precursors include, ethylene        oxide, propylene oxide, cyclopentene oxide, isobutylene oxide,        2,2,3-trimethyloxirane, butadienemonoxide, bicycloheptadiene        (also known as 2,5-norbornadiene), 1,2-epoxy-5-hexene,        2-methyl-2-vinyloxirane, 1-isopropyl-cyclohexa-1,3-diene and        tertbutylmethylether.

Optionally, the deposited film of the present invention can be heattreated at a temperature of not less than about 300° C. for a timeperiod of at least about 0.25 hour. Alternatively the deposited film ofthe present invention can be UV or e-beam treated, as described, forexample, in U.S. patent application Ser. No. 10/758,724, the content ofwhich is incorporated herein by reference.

The inventive method may further comprise the step of providing aparallel plate reactor, which has a area of a substrate chuck betweenabout 300 cm² and about 800 cm², and a gap between the substrate and atop electrode between about 1 cm and about 10 cm.

Alternatively, a multi-station reactor can also be employed for the filmdeposition. A high frequency RF power is applied to one of theelectrodes at a frequency between about 12 MHz and about 15 MHz.Optionally, an additional low frequency power, for example at 2 MHz orlower frequency (350-450 KHz), can be applied to one of the electrodes.

The heat-treating step may further be conducted at a temperature nothigher than about 300° C. for a first time period and then at atemperature not lower than about 380° C. for a second time period, thesecond time period being longer than the first time period. The secondtime period may be at least about 10 times the first time period. Thethermally treated film may optionally be treated by exposure to UVradiation or e-beam, such as described in U.S. patent application Ser.No. 10/758,724.

The deposition step for the ultralow k film of the present invention mayfurther comprise the steps of: setting the substrate temperature atbetween about 25° C. and about 400° C.; setting the high frequency RFpower density at between about 0.05 W/cm² and about 3.5 W/cm²; settingthe first precursor flow rate at between about 5 sccm and about 1000sccm; setting the flow rate of the second precursor between about 5 sccmand about 1000 sccm; setting the carrier gas (He) flow rate at between 0sccm and 1000 sccm; and setting the reactor pressure at a pressurebetween about 50 mtorr and about 8000 mtorr. Optionally, an ultralowfrequency power may be added to the plasma between about 10 W and about300 W.

In another preferred embodiment, there is provided a method forfabricating an ultralow k film comprising the steps of: providing aparallel plate type chemical vapor deposition reactor that has plasmaenhancement; positioning a pre-processed wafer on a substrate chuckwhich has a area of between about 300 cm² and about 800 cm² andmaintaining a gap between the wafer and a top electrode between about 1cm and about 10 cm; flowing a first precursor gas comprising silanederivative molecules having the molecular formula SiRR′R″R′″ wherein R,R′, R″ and R′″ are the same or different and are selected from H, alkyl,and alkoxy, where R, R′, R″ and R′″ are each independently of one othermethyl, ethyl, methoxy or ethoxy, into the reactor; flowing at least asecond precursor gas comprising organic molecules from the group ofcompounds including

-   -   where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and        are selected from hydrogen, alkyl, alkenyl or alkynyl groups        that may be linear, branched, cyclic, polycyclic and may be        functionalized with oxygen, nitrogen or fluorine containing        substituents; and depositing an ultralow k film on the wafer.

The process may further comprise the step of heat-treating the filmafter the deposition step at a temperature of not less than about 300°C. for at least about 0.25 hour or the step of UV or e-beam treating thefilm after the deposition. The process may further comprise the step ofapplying a RF power to the wafer. The heat-treating step may further beconducted at a temperature of not higher than about 300° C. for a firsttime period and then at a temperature not lower than about 380° C. for asecond time period, the second time period being longer than the firsttime period. The second time period may be at least about 10 times thefirst time period.

The silane derivative precursor utilized can be diethoxymethylsilane(DEMS) and the organic precursor can be bicycloheptadiene (BCHD). Thedeposition step for the ultralow k film may further comprise the stepsof: setting the wafer temperature at between about 25° C. and about 400°C.; setting a RF power density at between about 0.05 W/cm² and about 3.5W/cm²; setting the flow rate of the silane derivative between about 5sccm and about 1000 sccm; setting the flow rate of the organic precursorbetween about 5 sccm and about 1000 sccm; setting the carrier gas (He)flow rate at between 0 sccm and 1000 sccm; and setting the pressurereactor at between about 50 mtorr and about 8000 mtorr. Additionally,the deposition step may further comprise setting a flow ratio ofbicycloheptadiene to diethoxymethylsilane to between about 0.1 and about3, preferably between 0.2 and 0.6. The conductive area of the substratechuck can be changed by a factor X, which leads to a change in RF powerby the same factor X.

In still another preferred embodiment, there is provided a method forfabricating a thermally stable ultralow k dielectric film comprising thesteps of: providing a plasma enhanced chemical vapor deposition reactorof a parallel plate type; positioning a wafer on a substrate chuck thathas a conductive area between about 300 cm² and about 800 cm² andmaintaining a gap between the wafer and a top electrode between about 1cm and about 10 cm; flowing a precursor gas mixture of the foregoingmentioned silane derivative with an organic molecule into the reactorover the wafer, which is kept at a temperature between about 25° C. andabout 400° C., at a total flow rate between about 25 sccm and about 1000sccm while keeping the reactor pressure at between about 100 mtorr andabout 8000 mtorr; depositing a dielectric film on the wafer under a RFpower density between about 0.25 W/cm² and about 3 W/cm²; and optionallyannealing the ultralow k film at a temperature of not less than about300° C. for at least about 0.25 hour.

The inventive method may further comprise the step of annealing the filmat a temperature of not higher than about 300° C. for a first timeperiod and then at a temperature not lower than about 380° C. for asecond time period, wherein the second time period is longer than thefirst time period. The second time period may be set at least about 10times the first time period. The silane derivative can bediethoxymethylsilane (DEMS) and the organic precursor can bebicycloheptadiene (BCHD).

The present invention is further directed to an electronic structurewhich has layers of insulating materials as intralevel or interleveldielectrics in a back-end-of-the-line (“BEOL”) interconnect structurewhich includes a pre-processed semiconducting substrate that has a firstregion of metal embedded in a first layer of insulating material, afirst region of conductor embedded in a second layer of insulatingmaterial of the inventive ultralow k dielectric which comprises Si, C, Oand H, and a multiplicity of nanometer-sized pores, and having adielectric constant of not more than about 2.5, the second layer ofinsulating material being in intimate contact with the first layer ofinsulating material, the first region of conductor being in electricalcommunication with the first region of metal, and a second region ofconductor being in electrical communication with the first region ofconductor and being embedded in a third layer of insulating materialcomprising the inventive ultralow k dielectric, the third layer ofinsulating material being in intimate contact with the second layer ofinsulating material. The electronic structure may further comprise adielectric cap layer situated in-between the second layer of insulatingmaterial and the third layer of insulating material. The electronicstructure may further comprise a first dielectric cap layer between thesecond layer of insulating material and the third layer of insulatingmaterial, and a second dielectric cap layer on top of the third layer ofinsulating material.

The dielectric cap material can be selected from silicon oxide, siliconnitride, silicon oxynitride, silicon carbon nitride (SiCN), siliconcarbon oxynitride (SiCON), refractory metal silicon nitride (wherein therefractory metal is selected from the group consisting of Ta, Zr, Hf andW), silicon carbide, carbon doped oxide or SiCOH and their hydrogenatedcompounds. The first and the second dielectric cap layers may beselected from the same group of dielectric materials. The first layer ofinsulating material may be silicon oxide or silicon nitride or dopedvarieties of these materials, such as phosphorus silicate glass (“PSG”)or boron phosphorus silicate glass (“BPSG”). The electronic structuremay further include a diffusion barrier layer of a dielectric materialdeposited on at least one of the second and third layers of insulatingmaterial. The electronic structure may further comprise a dielectric ontop of the second layer of insulating material, which acts as a reactiveion etch (“RIE”) hard mask and polish stop layer and a dielectricdiffusion barrier layer on top of the dielectric RIE hard mask andpolish stop layer. The electronic structure may further comprise a firstdielectric RIE hard mask/polish-stop layer on top of the second layer ofinsulating material, a first dielectric RIE hard mask/diffusion barrierlayer on top of the first dielectric polish-stop layer, a seconddielectric RIE hard mask/polish-stop layer on top of the third layer ofinsulating material, and a second dielectric diffusion barrier layer ontop of the second dielectric polish-stop layer. The electronic structuremay further comprise a dielectric cap layer of same materials asmentioned above, between an interlevel dielectric of ultralow kdielectric and an intralevel dielectric of ultralow k dielectric.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing objects, features and advantages of the present inventionwill become apparent from the following detailed description and theappended drawings in which:

FIG. 1 depicts a cross-sectional view of a parallel plate chemical vapordeposition reactor that can be employed in the present invention.

FIG. 2 depicts a Fourier Transform Infrared (“FTIR”) spectrum obtainedfrom an inventive ultralow k material deposited from a mixture ofdiethoxymethylsilane (“DEMS”) and bicycloheptadiene (“BCHD”).

FIG. 3 depicts a Fourier Transform Infrared (“FTIR”) spectrum obtainedfrom another inventive ultralow k material deposited from a mixture ofdiethoxymethylsilane (“DEMS”) and cyclopentene oxide (“CPO”).

FIG. 4 depicts an enlarged, cross-sectional view of an electronic devicehaving an intralevel dielectric layer and an interlevel dielectric layerof ultralow k material according to the present invention.

FIG. 5 depicts an enlarged, cross-sectional view of the electronicstructure of FIG. 4 having an additional diffusion barrier dielectriccap layer on top of ultralow k material film according to the presentinvention.

FIG. 6 depicts an enlarged, cross-sectional view of the electronicstructure of FIG. 5 having an additional RIE hard mask/polish-stopdielectric cap layer and dielectric cap diffusion barrier on top of thepolish-stop layer according to the present invention.

FIG. 7 depicts an enlarged, cross-sectional view of the electronicstructure of FIG. 6 having additional RIE hard mask/polish-stopdielectric layers on top of the interlevel ultralow k material filmaccording to the present invention.

FIG. 8 is an enlarged, cross-sectional view of the present inventionelectronic structure of FIG. 7 having additional RIE hard mask/polishstop dielectric layers deposited on top of the multiphase material film.

DETAILED DESCRIPTION OF THE INVENTION

The present invention discloses a method for fabricating a thermallystable ultralow dielectric constant film in a parallel plate plasmaenhanced chemical vapor deposition (“PECVD”) reactor. The materialdisclosed in the preferred embodiment contains a matrix of ahydrogenated oxidized silicon carbon material (SiCOH) comprising Si, C,O and H in a random covalently bonded network and having a dielectricconstant of not more than about 2.5, which may further contain molecularscale voids, approximately 0.5 to 20 nanometer in diameter, furtherreducing the dielectric constant to values below about 2.0. Morepreferably, the dielectric constant for the ultralow k film is fromabout 1.5 to about 2.5, and most preferably the dielectric constant isfrom about 1.8 to about 2.25. The ultralow k dielectric material of thepresent invention is typically characterized as a multiphase film thatincludes a first phase consists essentially of Si, C, O and H and at asecond phase that consists essentially of C and H, and a multiplicity ofnanometer-sized pores.

To produce an ultralow k thermally stable film, a specific geometry ofthe deposition reactor with specific growth conditions is necessary. Forinstance, in the parallel plate reactor, a conductive area of thesubstrate chuck should be between about 300 cm² and about 800 cm², witha gap between the substrate and a top electrode between about 1 cm andabout 10 cm. A RF power is applied to the substrate. In accordance withthe present invention, the ultralow k film is formed from a mixture of asilane derivative such as DEMS and a second precursor, which is anorganic molecule, selected from the group of compounds including

-   -   where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and        are selected from hydrogen, alkyl, alkenyl or alkynyl groups        that may be linear, branched, cyclic, polycyclic and may be        functionalized with oxygen, nitrogen or fluorine containing        substituents, such as bicycloheptadiene (BCHD), in a        specifically configured deposition reactor under specific        reaction conditions. The ultralow k film of the present        invention can further be heat treated at a temperature not less        than about 300° C. for at least about 0.25 hour or to reduce the        dielectric constant. The film can also be UV or e-beam treated        after deposition or after the thermal heat treatment. During        this post-deposition treatment step, molecule fragments derived        from the second precursor gas (or gas mixture) comprising carbon        and hydrogen and optionally oxygen atoms may thermally decompose        and may be converted into smaller molecules which are released        from the film. Optionally, further development of voids may        occur in the film by the process of conversion and release of        the molecule fragments. The film density is thus decreased, with        corresponding decrease in dielectric constant and refractive        index.

The present invention provides a method for preparing a material thathas an ultralow k, i.e., lower than about 2.5, which is suitable forintegration in a BEOL wiring structure. More preferably, the dielectricconstant for the inventive ultralow k film is from about 1.5 to about2.5 and, most preferably, the dielectric constant is from about 1.8 toabout 2.25. The inventive films can be prepared by choosing at least twosuitable precursors and a specific combination of processing parametersas described herein below. Preferably, the first precursor is selectedfrom silane (SiH₄) derivatives having the molecular formula SiRR′R″R′″where R,R′,R″, and R′″ may or may not be identical and are selected fromH, alkyl, and alkoxy, preferably methyl, ethyl, methoxy, and ethoxy.Preferred precursors include: diethoxydimethylsilane,diethoxymethylsilane (DEMS), ethoxyltrimethylsilane,ethoxydimethylsilane, dimethoxydimethylsilane, dimethoxymethylsilane,triethoxysilane, and trimethoxymethylsilane.

The second precursor employed in the present application is an organiccompound selected from:

-   -   where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and        are selected from hydrogen, alkyl, alkenyl or alkynyl groups        that may be linear, branched, cyclic, polycyclic and may be        functionalized with oxygen, nitrogen or fluorine containing        substituents. Additionally, other atoms such as S, Si, or other        halogens may be contained in the second precursor molecule. Of        these species, the most suitable are ethylene oxide, propylene        oxide, cyclopentene oxide, isobutylene oxide,        2,2,3-trimethyloxirane, butadienemonoxide, bicycloheptadiene,        1,2-epoxy-5-hexene, 2-methyl-2-vinyloxirane,        1-isopropyl-cyclohexa-1,3-diene and tertbutylmethylether.

As shown in FIG. 1, parallel plate plasma enhanced chemical vapordeposition (“PECVD) reactor 10 is the type used for processing 200 mmwafers. The inner diameter, X, of the reactor 10 is approximately 13inches, while its height, Y, is approximately 8.5 inches. The diameterof substrate chuck 12 is approximately 10.8 inches. Reactant gases areintroduced into reactor 10 through a gas distribution plate (“GDP”) 16that is spaced apart from substrate chuck 12 by a gap Z of about 1 inch,and are exhausted out of reactor 10 through a 3-inch exhaust port 18. RFpower 20 is connected to GDP 16, which is electrically insulated fromreactor 10, and substrate chuck 12 is grounded. For practical purposes,all other parts of the reactor are grounded. In a different embodiment,RF power 20 can be connected to substrate chuck 12 and transmitted tosubstrate 22. In this case, the substrate acquires a negative bias,whose value is dependent on the reactor geometry and plasma parameters.In another embodiment, more than one electrical power supply can beused. For instance, two power supplies can operate at the same RFfrequency, or one may operate at a low frequency and one at a highfrequency. The two power supplies may be connected both to the sameelectrode or to separate electrodes. In another embodiment, the RF powersupply can be pulsed on and off during deposition. Process variablescontrolled during deposition of the low-k films are RF power density,precursor mixture and flow rate, pressure in reactor, electrode spacing,and substrate temperature. (The temperature of the heated wafer chuckcontrols the substrate temperature.)

In accordance with the present invention, suitable first and secondprecursors and specific combination of processing parameters describedherein above are employed such that the inventive ultralow k materialprepared preferably comprises: between about 5 and about 40 atomicpercent of Si; between about 5 and about 70 atomic percent of C; between0 and about 50 atomic percent of O; and between about 5 and about 55atomic percent of H. In some embodiments of the present invention, the Ccontent could be as high as about 70%.

The main process variables controlled during a deposition process for afilm are the RF power, the flow rates of the precursors, the reactorpressure and the substrate temperature. Provided herein below areseveral examples of deposition of films from a first precursordiethoxymethylsilane (DEMS) and a second precursor bicycloheptadiene(BCHD) according to the present invention. In some examples, the DEMSprecursor vapors were transported into the reactor by using He (or Ar)as a carrier gas. Optionally, the films were heat treated at 400° C.after deposition to reduce k. Alternatively the films were UV or e-beamtreated to reduce k and increase cross-linking, as described, forexample, in U.S. application Ser. No. 10/758,724. The heat treatment canbe used alone or in conjunction with one of treatment methods disclosedin the '724 application.

Specifically, the as deposited film can be optionally treated using anenergy source, in accordance with the '724 application, to stabilize thefilm and improve its properties (electrical, mechanical, adhesive),resulting in a final optimum film. Suitable energy sources includethermal, chemical, ultraviolet (UV) light, electron beam (e-beam),microwave, and plasma. Combinations of the aforementioned energy sourcescan also be used in the present invention. The energy sources employedin the present invention are utilized to modify the Si—O bonding networkof the as deposited dielectric, modify other bonds in the material,cause more Si—O cross-linking, and in some cases to remove thehydrocarbon phase, with all of the aforementioned modificationsresulting in a higher elastic modulus, a higher hardness, or a lowerinternal stress, or a combination of said properties. Either a highermodulus or a lower stress results in a lower crack propagation velocity,with the combination of higher modulus and lower stress being apreferred result of the energy treatment.

The thermal energy source includes any source such as, for example, aheating element or a lamp, that can heat the deposited dielectricmaterial to a temperature from about 300° to about 500° C. Morepreferably, the thermal energy source is capable of heating thedeposited dielectric material to a temperature from about 350° to about430° C. This thermal treatment process can be carried out for varioustime periods, with a time period from about 1 minute to about 300minutes being typical. The thermal treatment step is typically performedin the presence of an inert gas such as He and Ar. The thermal treatmentstep may be referred to as an anneal step in which rapid thermal anneal,furnace anneal, laser anneal or spike anneal conditions are employed.

The UV light treatment step is performed utilizing a source that cangenerate light having a wavelength from about 500 to about 150 nm, toirradiate the substrate while the wafer temperature is maintained at 25°to 500° C., with temperatures from 300°-450° C. being preferred.Radiation with >370 nm is of insufficient energy to dissociate oractivate important bonds, so the wavelength range 150-370 nm is apreferred range. Using literature data and absorbance spectra measuredon as deposited films, the inventors have found that <170 nm radiationmay not be favored due to degradation of the SiCOH film. Further, theenergy range 310-370 nm is less useful than the range 150-310 nm, due tothe relatively low energy per photon from 310-370 nm. Within the 150-310nm range, optimum overlap with the absorbance spectrum of the asdeposited film and minimum degradation of the film properties (such ashydrophobicity) may be optionally used to select a most effective regionof the UV spectrum for changing the SiCOH properties.

The electron beam treatment step is performed utilizing a source that iscapable of generating a uniform electron flux over the wafer, withenergies from 0.5 to 25 keV and current densities from 0.1 to 100microAmp/cm² (preferably 1 to 5 microAmp/cm²), while the wafertemperature is maintained at 25° to 500° C., with temperatures from300°-450° C. being preferred. The preferred dose of electrons used inthe electron beam treatment step is from 50 to 500 microcoulombs/cm²,with 100 to 300 microcoulombs/cm² being most preferred.

The plasma treatment step is performed utilizing a source that iscapable of generating atomic hydrogen (H), and optionally CH₃ or otherhydrocarbon radicals. Downstream plasma sources are preferred overdirect plasma exposure. During plasma treatment the wafer temperature ismaintained at 25° to 500° C., with temperatures from 300°-450° C. beingpreferred.

The plasma treatment step is performed by introducing a gas into areactor that can generate a plasma and thereafter it is converted into aplasma. The gas that can be used for the plasma treatment includes inertgases such as Ar, N, He, Xe or Kr, with He being preferred; hydrogen orrelated sources of atomic hydrogen, methane, methylsilane, relatedsources of CH₃ groups, and mixtures thereof. The flow rate of the plasmatreatment gas may vary depending on the reactor system being used. Thechamber pressure can range anywhere from 0.05 to 20 torr, but thepreferred range of pressure operation is 1 to 10 torr. The plasmatreatment step occurs for a period of time, which is typically fromabout ½ to about 10 minutes, although longer times may be used withinthe invention.

An RF or microwave power source is typically used to generate the aboveplasma. The RF power source may operate at either the high frequencyrange (on the order of about 100 W or greater); the low frequency range(less than 250 W) or a combination thereof may be employed. The highfrequency power density can range anywhere from 0.1 to 2.0 W/cm² but thepreferred range of operation is 0.2 to 1.0 W/cm². The low frequencypower density can range anywhere from 0.1 to 1.0 W/cm² but the preferredrange of operation is 0.2 to 0.5 W/Cm². The chosen power levels must below enough to avoid significant sputter etching of the exposeddielectric surface (<5 nanometers removal).

The deposition conditions utilized are also critical to enable asuccessful implementation of the deposition process according to thepresent invention. For instance, a wafer temperature of between about25° C. and about 420° C., and preferably of between about 60° C. andabout 350° C. is utilized. A RF power density between about 0.05 W/cm²and about 3.5 W/cm², and preferably between about 0.25 W/cm² and about 1W/cm² is utilized. In the preferred process, radio frequency energy isapplied to both the gas introduction plate (“showerhead”) at a frequencyof 13.6 MHz and a power of about 350 W (although 200-450 W may be used),and also to the wafer chuck at a frequency of 13.6 MHz and a power ofabout 100 W (although 50-200 W may be used). As is known in the art,different RF frequencies (0.26, 0.35, 0.45 MHz) may also be used in thepresent invention.

A reactant gas flow rate of DEMS between about 5 sccm and about 1000sccm, and preferably between about 25 sccm and about 200 sccm isutilized. A reactant gas flow rate of BCHD between about 5 sccm andabout 1000 sccm, and preferably between about 10 sccm and about 120 sccmis utilized. When liquid precursor delivery is used, a liquid flow rateis used in the range of 500-5000 mg/minute for each of the precursors.Optionally, He may be added and the preferred He flow is in the range100-2000 sccm, although other flows may be used within the invention.Reactor pressure during the deposition process is typically betweenabout 50 mtorr and about 10000 mtorr.

If a multistation deposition reactor is used, the area of the substraterefers to each individual substrate chuck and the flow rates of thegases refer to one individual deposition station. Accordingly, totalflow rates and total power input to the reactor are multiplied by atotal number of deposition stations inside the reactor.

The deposited films are stabilized before undergoing further integrationprocessing. The stabilization process can be performed in afurnace-annealing step at about 300° C. to about 430° C. for a timeperiod between about 0.5 hours and about 4 hours. The stabilizationprocess can also be performed in a rapid thermal annealing process attemperatures above about 300° C. The stabilization process can also beperformed in a UV or e-beam chamber at temperatures above 300° C. Thedielectric constants of the films obtained according to the presentinvention are lower than about 2.5. The thermal stability of the filmsobtained according to the present invention in a non-oxidizing ambientis up to at least a temperature of about 430° C.

The electronic devices formed according to the present invention areshown in FIGS. 4-7. It should be noted that the devices shown in FIGS.4-7, are merely illustrated as examples according to the presentinvention, while countless other devices can also be formed according tothe present invention.

FIG. 4 depicts electronic device 30 that is built on a silicon substrate32. On top of silicon substrate 32, insulating material layer 34 isformed with a first region of metal 36 embedded therein. After achemical mechanical polishing (“CMP”) process is conducted on firstregion of metal 36, a film such as an ultralow k film 38 is deposited ontop of first layer of insulating material 34 and first region of metal36. Optionally, an additional dielectric cap layer (not shown) may beadded between layer 34 and layer 38. First layer of insulating material34 may be suitably formed of silicon oxide, silicon nitride, dopedvarieties of these materials, or any other suitable insulatingmaterials. Ultralow k film 38 is patterned by a photolithography processand conductor layer 40 is deposited therein. After a CMP process onfirst conductor layer 40 is carried out, second layer of ultralow k film44 is deposited by a plasma enhanced chemical vapor deposition (“PECVD”)process overlying first ultralow k film 38 and first conductor layer 40.Conductor layer 40 may be deposited of a metallic conductive material ora non-metallic conductive material. For instance, a metallic conductivematerial of aluminum or copper, or a non-metallic material such asnitride or polysilicon may be utilized. First conductor 40 is inelectrical communication with first region of metal 36.

A second region of conductor 50 is formed, after a photolithographicprocess in second ultralow k film layer 44 is conducted, followed by adeposition process for the second conductor material. Second conductor50 may also be deposited of either a metallic material or a non-metallicmaterial, similar to that used in depositing the first conductor layer40. The second region of conductor 50 is in electrical communicationwith the first region of conductor 40 and is embedded in the secondlayer of ultralow k insulator 44. The second layer of ultralow k film isin intimate contact with the first layer of insulating material 38. Inthis specific example, the first layer of insulating material 38, whichis an ultralow k material according to the present invention, serves asan intralevel dielectric material, while the second layer of insulatingmaterial, i.e., the ultralow k film 44, serves as both an intralevel andan interlevel dielectric. Based on the low dielectric constant of theultralow k film, superior insulating property can be achieved by firstinsulating layer 38 and second insulating layer 44.

FIG. 5 depicts electronic device 60 according to the present invention,similar to that of electronic device 30 shown in FIG. 4, but withadditional dielectric cap layer 62 deposited between first insulatingmaterial layer 38 and second insulating material layer 44. Dielectriccap layer 62 can be suitably formed of a material such as silicon oxide,silicon nitride, silicon oxynitride, silicon carbide, silicon carbonnitride (SiCN) silicon carbo-oxide (SiCO), modified ultralow k and theirhydrogenated compounds, as well as refractory metal silicon nitride,wherein the refractory metal is selected the group consisting of: Ta,Zr, Hf, and W. Additionally dielectric cap layer 62 functions as adiffusion barrier layer for preventing diffusion of first conductorlayer 40 into second insulating material layer 44 or into the lowerlayers, especially into layers 34 and 32.

FIG. 6 depicts another alternate embodiment of electronic device 70according to the present invention. In electronic device 70, twoadditional dielectric cap layers 72 and 74 that act as an RIE mask andCMP (chemical-mechanical polishing) polish stop layer are used. Firstdielectric cap layer 72 is deposited on top of first insulating materiallayer 38. The function of dielectric layer 72 is to provide an end pointfor the CMP process utilized in planarizing first conductor layer 40.Polish stop layer 72 can be deposited of a suitable dielectric materialsuch as silicon oxide, silicon nitride, silicon oxynitride, siliconcarbide, silicon carbo-oxide (SiCO), silicon carbon nitride (SCN)modified ultralow k and their hydrogenated compounds, as well asrefractory metal silicon nitride, wherein the refractory metal isselected from the group consisting of: Ta, Zr, Hf and W. The top surfaceof dielectric layer 72 is at the same level as first conductor layer 40.A second dielectric layer 74 can be added on top of second insulatingmaterial layer 44 for the same purposes.

FIG. 7 depicts still another alternate embodiment of electronic device80 according to the present invention. In this alternate embodiment, anadditional layer of dielectric 82 is deposited and thus divides secondinsulating material layer 44 into two separate layers 84 and 86.Intralevel and interlevel dielectric layer 44, as depicted in FIG. 7, istherefore divided into interlayer dielectric layer 84 and intraleveldielectric layer 86 at the boundary between interconnect 92 andinterconnect 94, as depicted in FIG. 8. An additional diffusion barrierlayer 96 is further deposited on top of the upper dielectric layer 74.The additional benefits provided by this alternate embodiment of theelectronic structure 80 is that the dielectric layer 82 acts as a RIEetch stop providing superior interconnect depth control, and hencesuperior control over the conductor resistance.

The following examples are presented to illustrate the fabrication ofthe ultralow k dielectric film in accordance with the present inventionas well as to demonstrate advantages that can be obtained therefrom:

EXAMPLE 1

In this example, according to FIG. 1, a wafer was first prepared byintroducing the wafer into reactor 10 through a slit valve 14 and thewafer was optionally pre-etched by argon gas. In this wafer preparationprocess, the wafer temperature was set at about 180° C. and the argonflow rate was set at about 25 sccm, to achieve a pressure of about 100mtorr. A RF power was then turned on to about 125 W for about 60seconds. The RF power and the argon gas flow were then turned off.

The DEMS precursor was carried into the reactor. The ultralow k filmaccording to the present invention was deposited by first establishinggas flows of DEMS and BCHD to desired flow rates and pressure, i.e., atabout 4 sccm of DEMS and about 3 sccm of BCHD and about 500 mtorr. A RFpower was then turned on at about 30 W for a time period of about 50minutes. The RF power and the gas flow were then turned off. The waferwas then removed from reaction reactor 10.

To reduce the dielectric constant of the deposited films and to furtherimprove their thermal stability, i.e., to make them stable attemperatures greater than 300° C., the films were post treated toevaporate the volatile contents and to dimensionally stabilize thefilms. The post treatment process can be carried out in an annealingfurnace by the following steps. The furnace was first purged for about 5minutes (with the film samples in a load station) with nitrogen at aflow rate of about 10 liters/minute. The film samples were thentransferred into the furnace reactor to start the post annealing cycleof heating the films to about 280° C. at a heating rate of about 5°C./minute, holding at about 280° C. for about 5 minutes, heating at asecond heating rate of about 5° C./minute to about 400° C., holding atabout 400° C. for about 4 hours, turning the furnace off and allowingthe film samples to cool to a temperature of below about 100° C. Asuitable first holding temperature may be between about 280° C. andabout 300° C., while a suitable second holding temperature may bebetween about 300° C. and about 400° C. The films thus obtained have adielectric constant of 1.81. Alternatively the film can be UV or e-beamtreated at above 300° C. for up to 30 minutes.

Results of the first embodiment are now discussed in reference to FIG.2. FIG. 2 presents the FTIR spectrum obtained from an ultralow k filmprepared from a mixture of DEMS+BCHD in accordance with the presentinvention. The spectrum displays the Si—O absorption band at about1000-1100 cm⁻¹, Si—CH₃ absorption peak at about 1268 cm⁻¹ and C—Habsorption peaks at about 2900-3000 cm⁻¹. One characteristic of the FTIRspectrum of the ultralow k film is the Si—O peak can be deconvolutedinto 3 peaks centered at 1141 cm⁻¹, 1064 cm⁻¹ and 1030 cm⁻¹,asparticularly illustrated in FIG. 2.

EXAMPLE 2

In this example, a wafer was prepared in the same tool as in Example 1.The wafer was first introduced into the reaction chamber. The wafertemperature was set at about 180° C. The DEMS precursor was carried intothe reactor. The ultralow k film according to the present invention wasdeposited by first establishing gas flows of DEMS and butadienemonoxide(BMO) to desired flow rates and pressure, i.e., at about 1 sccm of DEMSand about 4 sccm of BMO and about 500 mtorr. A RF power was then turnedon at about 30 W for a time period of about 50 minutes. The RF power andthe gas flow were then turned off. The wafer was then removed fromreactor 10.

The film was then treated with the same method described in Example 1.The resulting film had a dielectric constant of 1.77.

EXAMPLE 3

In this example, a wafer was prepared in the same tool as in Example 1.The wafer was first introduced into the reaction chamber. The wafertemperature was set at about 180° C. The DEMS precursor was carried intothe reactor. The ultralow k film according to the present invention wasdeposited by first establishing gas flows of DEMS and2-methyl-2-vinyloxirane (MVOX) to desired flow rates and pressure, i.e.,at about 2 sccm of DEMS and about 3 sccm of MVOX and about 500 mtorr. ARF power was then turned on at about 30 W for a time period of about 50minutes. The RF power and the gas flow were then turned off. The waferwas then removed from reactor 10.

The film was then treated with the same method described in Example 1.

The resulting film had a dielectric constant of 2.08.

EXAMPLE 4

In this example, a wafer was prepared in an 8-inch commercial PECVDtool. The wafer was first introduced into the reaction chamber. Thewafer temperature was set at about 200° C. Both DEMS and cyclopenteneoxide (CPO) were carried into the reactor using He as a carrier gas. Theultralow k film according to the present invention was deposited byfirst establishing gas flows of DEMS and CPO and He to desired flowrates and pressure, i.e., at about 70 sccm of DEMS and about 320 sccm ofCPO and about 300 sccm of He and about 2000 mtorr. A RF power was thenturned on at about 300W for a time period of about 10 minutes. The RFpower and the flow were then turned off. The wafer was then removed fromthe reaction chamber.

The film was then treated with the same method described in Example 1.The resulting film had a dielectric constant of 2.19.

Results are now discussed in reference to FIG. 3. FIG. 3 presents theFTIR spectrum obtained from an ultralow k film prepared from DEMS/CPOand He. The spectrum displays the Si—O absorption band at about1000-1100 cm⁻¹, S₁—CH₃ absorption peak at about 1267 cm⁻¹ and C—Habsorption peaks at about 2900-3000 cm⁻¹. One characteristic of the FTIRspectrum of the ultralow k film is the Si—O peak can be deconvolutedinto 3 peaks centered at 1132 cm⁻¹, 1058 cm⁻¹ and 1024 cm⁻¹, asparticularly illustrated in FIG. 3.

A rapid thermal annealing (“RTA”) process may also be used to stabilizeultralow k films. The films obtained according to the present invention,are characterized by dielectric constants k less than about 2.5, and arethermally stable for integration in a back-end-of-the-line (“BEOL”)interconnect structure, which is normally processed at temperatures ofup to about 400° C. The teachings of the present invention can thereforebe easily adapted in producing films as intralevel and interleveldielectrics in back-end-of-the-line processes for logic and memorydevices.

The method and electronic structures formed according to the presentinvention have therefore been thoroughly demonstrated in the abovedescriptions and in the appended drawings of FIGS. 4-8. It should beemphasized that the examples of the electronic structures shown in FIGS.4-8 are merely used to illustrate the inventive method that can beapplied in the fabrication of countless electronic devices.

As is known in the art, the gas flow units listed above in the 4 processexamples may be replaced by liquid flow units when liquid mass flowcontrol is used.

While the present invention has been described in an illustrativemanner, it should be understood that the terminology used is intended tobe in a nature of words of description rather than of limitation.

Furthermore, while the present invention has been particularly shown anddescribed with respect to a preferred embodiment and several alternateembodiments, it is to be appreciated that those skilled in the art mayreadily apply these teachings to other possible variations of thepresent invention without departing from the spirit and scope of thepresent invention.

The embodiments of the present invention in which exclusive property orprivilege is claimed are defined below in the appended claims.

1. A method for fabricating an ultralow dielectric constant filmcomprising the steps of: flowing a first precursor gas having a linearmolecular formula of SiRR′R″R′″, where R,R′,R″, and R′″ are the same ordifferent and are selected from H, alkyl, and alkoxy into a chamber of aplasma enhanced chemical vapor deposition (PECVD) reactor; flowing asecond precursor gas having one of the following formulas

where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and areselected from hydrogen, alkyl, alkenyl or alkynyl groups that may belinear, branched, cyclic, polycyclic and may be functionalized withoxygen, nitrogen or fluorine containing substituents into said chamber;and depositing an ultralow k film from said precursor gases on asubstrate.
 2. The method of claim 1 wherein said ultralow k film is amultiphase film that comprises a first phase consisting essentially ofSi, C, O and H and at least a second phase consisting essentially of C,H and a multiplicity of nanometer-sized pores on said substrate.
 3. Themethod of claim 1 further comprising mixing an inert gas with one orboth of said precursor gases.
 4. The method of claim 1 furthercomprising heating said ultralow k film after deposition at atemperature not less than about 300° C. for at least about 0.25 hours.5. The method of claim 1 further comprising treating said utralow k filmafter deposition with an energy source to stabilize the ultralow k filmand improve its properties, said energy source comprising one of athermal source, a chemical source, an ultraviolet (UV) light source, anelectron beam (e-beam) source, a microwave source, or a plasma source.6. The method of claim 1 wherein said ultralow k film has a dielectricconstant of not more than about 2.5.
 14. The method of claim 1 whereinsaid second precursor comprises bicycloheptadiene (BCHD), cyclopenteneoxide (CPO), ethylene oxide, propylene oxide, isobutylene oxide,2,2,3-trimethyloxirane, butadienemonoxide, 1,2-epoxy-5-hexene,2-methyl-2-vinyloxirane, tertbutylmethylether,1-isopropyl-cycloohexa-1,3-diene or mixtures thereof.
 15. The method ofclaim 1 wherein said step of depositing the ultralow k film furthercomprises the steps of setting a temperature for said substrate atbetween about 25° C. and about 400° C.; and setting a RF power densityat between about 0.05 W/cm² and about 3.5 W/cm².
 16. The method of claim1 wherein said step of depositing the ultralow k film further comprisessetting a flow rate for said first precursor gas between about 5 sccm toabout 1000 sccm, or between about 30 to about 6,000 mg/minute whenliquid delivery is used.
 17. The method of claim 16 wherein said flowrate for said first precursor gas is between about 25 seem to about 200seem, or between about 150 to about 1200 mg/minute when liquid deliveryis used.
 18. The method of claim 1 wherein said step of depositing saidultralow k film further comprises setting a flow rate for said secondprecursor gas between about 5 seem to about 1000 sccm, or between about30 to about 6,000 mg/minute when liquid delivery is used.
 9. The methodof claim 18 wherein said flow rate for said second precursor gas isbetween about 25 sccm to about 200 sccm, or between about 150 to about1200 mg/minute when liquid delivery is used.
 20. The method of claim 1wherein said step of depositing said ultralow k film further comprisessetting a pressure for said PECVD reactor at between about 50 mtorr andabout 10000 mtorr.
 21. The method of claim 20 wherein said pressure forsaid PECVD reactor is between about 100 mtorr and about 5000 mtorr. 22.The method of claim 1 wherein said step of depositing said ultralow kfilm further comprises setting a flow rate ratio of bicycloheptadiene,as said second precursor gas, to diethoxymethylsilane, as said firstprecursor gas, to between about 0.1 and about
 3. 23. The method of claim22 wherein said flow rate ratio of said bicycloheptadiene to saiddiethoxymethylsilane is between about 0.2 and about 0.6.
 24. The methodof claim 1 wherein said PECVD reactor is run in a continuous mode. 25.The method of claim 1 wherein said PECVD reactor is run in a pulsedmode.
 26. A method for fabricating a thermally stable ultralow k filmcomprising the steps of: providing a plasma enhanced chemical vapordeposition (PECVD) reactor; positioning a pre-processed wafer on asubstrate chuck having an area between about 300 cm² and about 800 cm²and maintaining a gap between said wafer and a top electrode betweenabout 1 cm and about 10 cm; flowing a first precursor gas comprisinglinear silane derivative molecules into said PECVD reactor; flowing atleast a second precursor gas comprising a compound having one of thefollowing formulas

where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and areselected from hydrogen, alkyl, alkenyl or alkynyl groups that may belinear, branched, cyclic, polycyclic and may be functionalized withoxygen, nitrogen or fluorine containing substituents into said PECVDreactor, and depositing an ultralow k film on said wafer.
 27. A methodfor fabricating a thermally stable ultralow k film comprising the stepsof: providing a plasma enhanced chemical vapor deposition (PECVD)reactor; positioning a wafer on a substrate chuck having an area betweenabout 300 cm² and about 800 cm², and maintaining a gap between the waferand a top electrode between about 1 cm and about 10 cm; flowing intosaid reactor over said wafer kept at a temperature between about 25° C.and about 400° C., a first precursor gas of a linear silane derivativeat a flow rate between about 5 sccm and about 1000 sccm, and a secondprecursor gas at a flow rate between about 5 sccm and about 1000 sccm,while keeping a pressure in said reactor between about 50 mtorr andabout 8000 mtorr, said second precursor gas comprising a compound havingone of the following formulas

where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and areselected from hydrogen, alkyl, alkenyl or alkynyl groups that may belinear, branched, cyclic, polycyclic and may be functionalized withoxygen, nitrogen or fluorine containing substituents; depositing anultralow k film on said wafer under a RF power density between about0.05 W/cm² and about 3.0 W/cm²; and treating said ultralow k film toimprove the stability of said film, said treating comprises an energysource selected from thermal, chemical, ultraviolet (UV) light, electronbeam (e-beam), microwave, plasma and a combination thereof.
 28. Themethod of claim 27 wherein said treating comprises annealing at atemperature not less than about 300° C. for at least about 0.25 hours.29. A dielectric material comprising elements of Si, C, O and H, saiddielectric material having a random covalently bonded tri-dimensionalnetwork structure, a dielectric constant of not more than 2.5 and anFTIR spectra having a Si—O absorption band that can be deconvoluted intothree peaks, said elements of Si, C, O and H are derived from a firstprecursor having the molecular formula SiRR′R″R′″ where R,R′,R″, and R′″are the same or different and are selected from H, alkyl, and alkoxy,and a second precursor having one of the following formulas

where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and areselected from hydrogen, alkyl, alkenyl or alkynyl groups that may belinear, branched, cyclic, polycyclic and may be functionalized withoxygen, nitrogen or fluorine containing substituents.
 30. The dielectricmaterial of claim 29 wherein said random covalently bondedtridimensional structure comprises Si—O, Si—C, Si—H, C—H and C—C bonds.31. The dielectric material of claim 29 wherein said dielectric materialis thermally stable to a temperature of at least 430° C.
 32. Thedielectric material of claim 29 wherein said dielectric material furthercomprises a multiplicity of nanometer-sized pores.
 33. The dielectricmaterial of claim 32 wherein diameters of said multiplicity ofnanometer-sized pores are between about 0.3 and about 50 nanometers. 34.A back-end-of-the-line (BEOL) interconnect structure comprising adielectric material as a BEOL insulator, cap or hardmask layer, saiddielectric material comprising elements of Si, C, O and H, and having arandom covalently bonded tri dimensional network structure, a dielectricconstant of not more than 2.5 and an FTIR spectra having a Si—Oabsorption band that can be deconvoluted into three peaks, said elementsof Si, C, O and H are derived from a first precursor having themolecular formula SiRR′R″R′″ where R,R′,R″, and R′″ are the same ordifferent and are selected from H, alkyl, and alkoxy, and a secondprecursor having one of the following formulas

where R¹, R²R³, R⁴, R⁵ and R⁶ may or may not be identical and areselected from hydrogen, alkyl, alkenyl or alkynyl groups that may belinear, branched, cyclic, polycyclic and may be functionalized withoxygen, nitrogen or fluorine containing substituents.
 35. An electronicstructure having layers of insulating material as intralevel orinterlevel dielectrics in a wiring structure comprising: a pre-processedsemiconducting substrate having a first region of metal embedded in afirst layer of insulating material; a first region of conductor embeddedin a second layer of insulating material formed of an ultralow kmaterial, said ultralow k material comprising Si, C, O and H, and amultiplicity of nanometer-sized pores, said ultralow k material having adielectric constant of not more than about 2.5 and an FTIR spectrahaving a Si—O absorption band that can be deconvoluted into three peaks,said elements of Si, C, O and H are derived from a first precursorhaving the molecular formula SiRR′R″R′″ where R,R′,R″, and R′″ are thesame or different and are selected from H, alkyl, and alkoxy, and asecond precursor having one of the following formulas

where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and areselected from hydrogen, alkyl, alkenyl or alkynyl groups that may belinear, branched, cyclic, polycyclic and may be functionalized withoxygen, nitrogen or fluorine containing substituents, said second layerof insulating material being in intimate contact with said first layerof insulating material, said first region of conductor being inelectrical communication with said first region of metal; and a secondregion of conductor being in electrical communication with said firstregion of conductor and being embedded in a third layer of insulatingmaterial comprising said ultralow k material, said third layer ofinsulating material being in intimate contact with said second layer ofinsulating material.
 36. The electronic structure of claim 35 furthercomprising a dielectric cap layer situated between said second layer ofinsulating material and said third layer of insulating material.
 37. Theelectronic structure of claim 35 further comprising a first dielectriccap layer between said second layer of insulating material and saidthird layer of insulating material; and a second dielectric cap layer ontop of said third layer of insulating material.
 38. The electronicstructure of claim 36 wherein said dielectric cap layer is formed of amaterial selected from the group consisting of silicon oxide, siliconnitride, silicon oxynitride, refractory metal silicon nitride, siliconcarbide, silicon carbon nitride, silicon carbo-oxide, and carbon dopedoxides and their hydrogen-containing compounds.
 39. The electronicstructure of claim 35 wherein said refractory metal silicon nitrideincludes a refractory metal selected from the group consisting of Ta,Zr, Hf and W.
 40. The electronic structure of claim 37 wherein saidfirst dielectric cap layer and said second dielectric cap layer areformed of a material selected from the group consisting of siliconoxide, silicon nitride, silicon oxynitride, refractory metal siliconnitride, silicon carbide, silicon carbon nitride, silicon carbo-oxide,carbon doped oxides and their hydrogen-containing compounds.
 41. Theelectronic structure of claim 40 wherein said refractory metal siliconnitride includes a refractory metal selected from the group consistingof Ta, Zr, Hf and W.
 42. The electronic structure of claim 35 whereinsaid first layer of insulating material is one selected from the groupconsisting of silicon oxide, silicon nitride, phosphosilicate glass(PSG), borophosphosilicate glass (BPSG), and other doped varieties ofthese materials.
 43. The electronic structure of claim 35 furthercomprising a diffusion barrier layer of a dielectric material depositedon at least one of said second layer of insulating material and saidthird layer of insulating material.
 44. The electronic structure ofclaim 35 further comprising a dielectric reactive ion etching (RIE) hardmask/polish stop layer on top of said second layer of insulatingmaterial, and a dielectric diffusion barrier layer on top of said RIEhard mask/polish stop layer.
 45. The electronic structure of claim 35further-comprising a first dielectric RIE hard mask/polish stop layer ontop of said second layer of insulating material; a first dielectricdiffusion barrier layer on top of said first dielectric RIE hardmask/polish stop layer, a second dielectric RIE hard mask/polish stoplayer on top of said third layer of insulating material; and a seconddielectric diffusion barrier layer on top of said second dielectric RIEhard mask/polish stop layer.
 46. The electronic structure of claim 45further comprising a dielectric cap layer between an interleveldielectric of an ultralow k material and an intralevel dielectric of anultralow k material.
 47. An electronic structure having layers ofinsulating material as intralevel or interlevel dielectrics in a wiringstructure comprising: a pre-processed semiconducting substrate having afirst region of metal embedded in a first layer of insulating material;and at least one first region of conductor embedded in at least onesecond layer of insulating material formed of an ultralow k material,said ultralow k material consisting essentially of Si, C, O and H, and amultiplicity of nanometer-sized pores, said ultralow k material having adielectric constant of not more than about 2.8 and an FTIR spectrahaving a Si—O absorption band can be deconvoluted into three peaks, saidelements of Si, C, O and H are derived from a first precursor having themolecular formula SiRR′R″R′″ where R,R′,R″, and R′″ are the same ordifferent and are selected from H, alkyl, and alkoxy, and a secondprecursor having one of the following formulas

where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and areselected from hydrogen, alky, alkenyl or atlkynyl groups that may belinear, branched, cyclic, polycyclic and may be functionalized withoxygen, nitrogen or fluorine containing substituents, one of said atleast one second layer of insulating material being in intimate contactwith said first layer of insulating material, one of said at least onefirst region of conductor being in electrical communication with saidfirst region of metal.
 48. The electronic structure of claim 47 furthercomprising a dielectric cap layer situated between each said at leastone second layer of insulating material.
 49. The electronic structure ofclaim 47 further comprising a first dielectric cap layer between each ofsaid at least one second layer of insulating material; and a seconddielectric cap layer on top of said topmost second layer of insulatingmaterial.
 50. The electronic structure of claim 49 wherein said firstdielectric cap layer and said second dielectric cap layer are formed ofan ultralow k material.
 51. The electronic structure of claim 49 whereinsaid first dielectric cap layer and said second dielectric cap layer areformed of a modified ultralow k material.
 52. The electronic structureof claim 49 wherein said dielectric cap layer is formed of a materialselected from the group consisting of silicon oxide, silicon nitride,silicon oxynitride, refractory metal silicon nitride, silicon carbide,silicon carbon nitride, silicon carbo-oxide, carbon doped oxides andtheir hydrogen-containing compounds.
 53. The electronic structure ofclaim 47 wherein said refractory metal silicon nitride includes arefractory metal selected from the group consisting of Ta, Zr, Hf and W.54. An electronic structure having layers of insulating material asintralevel or interlevel dielectrics in a wiring structure comprising: apre-processed semiconducting substrate having a first region of metalembedded in a first layer of insulating material; a first region ofconductor embedded in a second layer of insulating material, said secondlayer of insulating material being in intimate contact with said firstlayer of insulating material, said first region of conductor being inelectrical communication with said first region of metal; a secondregion of conductor being in electrical communication with said firstregion of conductor and being embedded in a third layer of insulatingmaterial, said third layer of insulating material being in intimatecontact with said second layer of insulating material; a firstdielectric cap layer between said second layer of insulating materialand said third layer of insulating material, and a second dielectric caplayer on top of said third layer of insulating material wherein saidfirst and said second dielectric cap layers are formed of an ultralow kdielectric material, said ultralow k material comprising Si, C, O and H,and a multiplicity of nanometer-sized pores, said ultralow k materialhaving a dielectric constant of not more than about 2.5 an FTIR spectrahaving a Si—O absorption band that can be deconvoluted into three peaks,said elements of Si, C, O and H are derived from a first precursorhaving the molecular formula SiRR′R″R′″ where R,R′,R″, and R′″ are thesame or different and are selected from H, alkyl, and alkoxy, and asecond precursor having one of the following formulas

where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and areselected from hydrogen, alkyl, alkenyl or alkynyl groups that may belinear, branched, cyclic, polycyclic and may be functionalized withoxygen, nitrogen or fluorine containing substituents.
 55. An electronicstructure having layers of insulating material as intralevel orinterlevel dielectrics in a wiring structure comprising: a pre-processedsemiconducting substrate having a first region of metal embedded in afirst layer of insulating material; a first region of conductor embeddedin a second layer of insulating material, said second layer ofinsulating material being in intimate contact with said first layer ofinsulating material, said first region of conductor being in electricalcommunication with said first region of metal; a second region ofconductor being in electrical communication with said first region ofconductor and being embedded in a third layer of insulating material,said third layer of insulating material being in intimate contact withsaid second layer of insulating material; and a diffusion barrier layerformed of a material comprising an ultralow k dielectric materialdeposited on at least one of said second layer and said third layer ofinsulating material, said ultralow k material comprising Si, C, O and H,and a multiplicity of nanometer-sized pores, said ultralow k materialhaving a dielectric constant of not more than about 2.5 and an FTIRspectra having a Si—O absorption band that can be deconvoluted intothree peaks, said elements of Si, C, O and H are derived from a firstprecursor having the molecular formula SiRR′R″R′″ where R,R′,R″, and R′″are the same or different and are selected from H, alkyl, and alkoxy,and a second precursor having one of the following formulas

where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and areselected from hydrogen, alkyl, alkenyl or alkynyl groups that may belinear, branched, cyclic, polycyclic and may be functionalized withoxygen, nitrogen or fluorine containing substituents.
 56. An electronicstructure having layers of insulating material as intralevel orinterlevel dielectrics in a wiring structure comprising: a pre-processedsemiconducting substrate having a first region of metal embedded in afirst layer of insulating material; a first region of conductor embeddedin a second layer of insulating material, said second layer ofinsulating material being in intimate contact with said first layer ofinsulating material, said first region of conductor being in electricalcommunication with said first region of metal; a second region ofconductor being in electrical communication with said first region ofconductor and being embedded in a third layer of insulating material,said third layer of insulating material being in intimate contact withsaid second layer of insulating material; a reactive ion etching (RIE)hard mask/polish stop layer on top of said second layer of insulatingmaterial, and a diff-usion barrier layer on top of said RIE hardmask/polish stop layer, wherein said RIE hard mask/polish stop layer andsaid diffusion barrier layer are formed of a an ultralow k dielectricmaterial, said ultralow k material comprising Si, C, O and H, and amultiplicity of nanometer-sized pores, said ultralow k material having adielectric constant of not more than about 2.5 and an FTIR spectrahaving a Si—O absorption band that can be deconvoluted into three peaks,said elements of Si, C, O and H are derived from a first precursorhaving the molecular formula SiRR′R″R′″ where R,R′,R″, and R′″ are thesame or different and are selected from H, alkyl, and alkoxy, and asecond precursor having one of the following formulas

where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and areselected from hydrogen, alkyl, alkenyl or alkynyl groups that may belinear, branched, cyclic, polycyclic and may be functionalized withoxygen, nitrogen or fluorine containing substituents.
 57. An electronicstructure having layers of insulating material as intralevel orinterlevel dielectrics in a wiring structure comprising: a pre-processedsemiconducting substrate having a first region of metal embedded in afirst layer of insulating material, a first region of conductor embeddedin a second layer of insulating material, said second layer ofinsulating material being in intimate contact with said first layer ofinsulating material, said first region of conductor being in electricalcommunication with said first region of metal; a second region ofconductor being in electrical communication with said first region ofconductor and being embedded in a third layer of insulating material,said third layer of insulating material being in intimate contact withsaid second layer of insulating material; a first RIE hard mask/polishstop layer on top of said second layer of insulating material; a firstdiffusion barrier layer on top of said first RIE hard mask/polish stoplayer; a second RIE hard mask/polish stop layer on top of said thirdlayer of insulating material; and a second diffusion barrier layer ontop of said second RIE hard mask/polish stop layer, wherein said RIEhard mask/polish stop layers and said diffusion barrier layers areformed of a ultralow k dielectric material comprising Si, C, O and H,and a multiplicity of nanometer-sized pores, said ultralow k materialhaving a dielectric constant of not more than about 2.8 and an FTIRspectra having a Si—O absorption band that can be deconvoluted intothree peaks, said elements of Si, C, O and H are derived from a firstprecursor having the molecular formula SiRR′R″R′″ where R,R′,R″, and R′″are the same or different and are selected from H, alkyl, and alkoxy,and a second precursor having one of the following formulas

where R¹, R², R³, R⁴, R⁵ and R⁶ may or may not be identical and areselected from hydrogen, alkyl, alkenyl or alkynyl groups that may belinear, branched, cyclic, polycyclic and may be functionalized withoxygen, nitrogen or fluorine containing substituents.
 58. The electronicstructure of claim 57 further comprising a dielectric cap layer formedof a material comprising said ultralow k dielectric material situatedbetween an interlevel dielectric layer and an intralevel dielectriclayer.
 59. The method of claim 1 wherein said PECVD reactor is aparallel plate reactor.
 60. The method of claim 1 further comprisingforming a plasma within said PECVD reactor.
 61. The method of claim 26wherein said PECVD reactor is a parallel plate reactor.
 62. The methodof claim 26 further comprising forming a plasma within said PECVDreactor.
 63. The method of claim 27 wherein said PECVD reactor is aparallel plate reactor.
 64. The method of claim 27 further comprisingforming a plasma within said PECVD reactor.